Control for power-operated aircraft guns



' 1951 E. c. M. DASSiS-FONSECA 5 214 83 CONTROL FOR POWER OPERATED AIRCRAFT GUNS Filed May 23, 1945 3 Sheets-Sheet 1 J v frwenir 25 55 l dfixzkiwca u ZZbrmys Feb. 20, 19 1 E. c. M. D'ASSlS-FONSECA 2,542,483

CONTROL FOR POWER OPERATED AIRCRAFT GUNS Feb. 20, 1951 E. c. M. D'ASSlS-FONSECA 2,542,433

CONTROL FOR POWER OPERATED AIRCRAFT GUNS 3 Sheets-Sheet 3 Filed May 25, 1945 axim m Patented Feb. 20, 1951 CONTROL FOR POWER-OPERATED AIRCRAFT GUNS Evelyn Cecil Muschamp dAssis-Fonseca, Bristol, England, assignor to The Bristol Aeroplane Company Limited, Bristol, England, a British company Application May 23, 1945, Serial No. 595,403 In Great Britain September 2, 1943 Section 1, Public Law 690,- August 8, 1946' Patent expires September 2, 1963' Claims.

This invention concerns guns for aircraft. Usually the gun is rotatableabout one axis to give the gun traverse and it also rotatable about asecond axis to elevate or depress the gun, and the gun is'fired' by a power-relay controlled by the gunner. Hereinafter it will be assumed that the-traverse of the gun takes place about a vertical axis and that the elevation of the gun occursabout a horizontal axis but it will be understood: that the guns can be mounted, or can assume inguse, any other position, and the expression field of fire will be used to mean the field coverediby theiull: range of both traverse and elevation.-

In gunsof this'kind, the gun has-a wide field of fire and generally can be trained on a target by'any of a number of d-ifierent combinations of traverse and elevation; It may happen that when the gun is trained in certain directions Within the field of fire it is not safe to fire the gunbecause some part of the aircraft lies in the direction of fire.- The object of this invention is to provide improved means for automatically preventing the gun being fired when it is so trained.

According to the-present invention, guns of the abovekind arecapable of beingtraversed and/or elevated at morethan one speed, and the-size of the'field of fire withinwhich the gun is prevented from firing is automatically varied to suit the prevailing conditions of said speed.

According to another feature of the invention the size of the initial or basic field of fire within which the gun is prevented from firing is automaticalyenlarged' as the speed of traverse and/or elevation is increased, said enlargement to the. initial size of said field taking place only on the side thereof which the gun first approaches.

When an electrical system of control is used for this purpose; it comprises a conducting plate, which-represents the field of fire, a contact movable over it inaccordance with the training movements of the gun, and insulated areas on the plate which represent the regions in which the firing is not safe, and the circuit through the contact member is interrupted by the insulation to prevent firing. When the present invention is applied to such asystem, the effective point of engagement of the contact with the plate is varied according totherate of' the training movements, and this may be accomplished by using auxiliary contacts, or by imparting additional movement to. the contact; as hereinafter described.

A- specifi'c. embodiment of the invention will now be described by way of example with reference to the accompanying drawings of which:

Figure 1 is a diagrammatic perspective view showing part of a mechanism in accordance with the present invention for automatically stopping the firing of a gun when the latter is trained in certain directions and an electrical circuit associated with said mechanism,

Figure 2 is a sectional elevation of mechanism in accordance withthe present invention, and

Figure 3' is a schematic front view of a gun turret for an aeroplane incorporating the mechanism of Figure 1.

The mechanism for automatically preventing firing is associated with guns 50 mounted in a turret 51 in which the traverse of the guns is produced solely by the rotation of the turret about a vertical axis. The turret comprises a transparent dome 52 in which the guns are mounted with the breech and actuating mechanism within the dome and the barrels extending through the dome. The guns 5!! are suitably carried by the turret 5! so as to be rotatable therewith and are supported upon a structure so as to be capable of elevation and depression.

The part of the turret already described extendsabove the fuselage 53 0f the aircraft and has a skirt dependingfrom it through a suitable opening into the fuselage. A suitable bearing. is. provided to support the turret where it enters the fuselage, for complete rotation.

The lower part 5 l of'the turret comprises a platform, a gunners seat carried thereby, ammunition boxes, and containers for spent ammunition, all of which are rotated with the turret as the guns are traversed;

The mechanism for rotating the turret and elevating the guns comprises a separate electric motor 55, 56 for each movement. The traversing motor 55 will drive, through reduction gearing, a gear wheel 5'! meshing with a fixed gear ring 25 secured to the part 54 of the turret. The elevat ng motor 55 will drive through reduction gearing, an elevating screw 51 co-operating with a nut 58 carried by the gun supports 59.

The gunners sighting apparatus is arranged in the upper part of the turret between the guns so as to be convenient to the gunner as is also a control handle 62 by which the rotation of the turret and the elevation and firing of the guns is-controlled. The firing is electrically controlled by a switch which upon being closed by the gunnercompletes a circuit toenergise a solenoid.

Referring to Figure l the fixed gear ring mentioned above is adapted to rotate a cylinder l through suitable gearing. The cylinder is also adapted to be raised and lowered with the movements of elevation and depression of the gun so that said cylinder rises or falls as the guns are elevated or depressed and also rotates as the guns are traversed with rotation of the turret. The cylinder is of electrically conducting material and has inserted in its face a number of non-conducting elements ||d (hereinafter referred to as images) each of which is an image of a zone or field of fire fire the guns. 1

Co-operating with the image-cylinder l0 are a set of three electrical brushes l2, l3 and M the central brush is of which is connected with a firing switch l5 whilst the pair of lateral brushes l2, M are respectively connected to two poles l6, I! of a selector switch l8. The latter is under the control of the traversing control handle and is so arranged that immediately upon said handle being moved to rotate the turret in one direction the selector switch I8 is closed to complete one circuit and upon the handle being set to produce a traverse in the other direction the selector switch is closed to complete another circuit. The circuit in each case comin which it is unsafe to of the gun is taking place) the selector switch I8 is open so that neither of the circuits leading from the lateral brushes |2, Hi to the firing solenoid l9 are completed.

Whilst the gun is thus being fired let it be assumed that the traversing control handle is actuated so as to produce rotation of the turret at a slow-rate towards a zone in which it is unsafe to continue firing the gun. As the turret is rotated the image-cylinder IE! will also be rotated for example in the direction indicated by arrow A in Figure 1. The actuation of the traversing control handle adjusts the selector-switch 4 l8 on to the contact I! for the contact I i which prises the firing switch Hi, the central brush l3,

the conducting image-cylinder H), a lateral brush |2 or M, the selector switch l8, a firing solenoid 9 and a battery 20. The firing of the guns is electrically controlled by the switch |5 which upon being closed by the gunner completes one or other of the circuits to the solenoid IS. The latter is then efiective to bring the firing mechanism into operation. l

The selector switch I8 is also connected to one side of a switch 2| which is normally closed. The other side of the switch 2| is connected with the image-cylinder I!) by way of conductor 22 and brush 24 so that whilst said switch is closed a circuit is completed from the cylinder to the switch 2|, the selector switch IS, the firing solenoid l9, and then by the battery 20 to the firing switch I5, the central brush [3 and the cylinder Ill.

The switch 2| is under the control of a governor 23 which is driven by the traversing motor through gears 51, 62 (Figure 1) and is so ad- 'justed that whilst the rate of traverse remains below a predetermined value (the slow-rate of traverse hereinafter referred to) the governor switch 2| is closed. However when the rate of traverse is raised above said predetermined value (the high-rate of traverse) the switch 2| is open. Y

The operation of the interrupter mechanism described and the conditions under which an enlargement of the unsafe field of fire should be provided for now follows:

Let it be assumed that the guns are stationary and are pointed in a direction in which it is safe to fire. When the firing switch |5 is closed a circuit is completed from the battery 20, the firing solenoid I9, the governor switch 2|, conductor 22, brushes 24 and I3, switch l5 and so back to the battery. Upon the solenoid l9 being thus energised the gun will commence to fire.

Under these circumstances (when no traverse may fire within this zone.

is the leading contact of the three l2, l3, M in respect of the movement of the image-cylinder l0 across them. At the instant at which the gun reaches the unsafe zone of fire, the image I In on the cylinder engages with the central conductor l3.

Prior to this engagement, the lateral brush M has been engaged by the image a and the circuit from said brush to the firing solenoid I9 which was completed by the closing of the selector switch I8 on contact I! when the traversing control handle was actuated, is broken. The breaking of this circuit has no effect however, since the circuit to the firing solenoid l9 through the central brush l3, contact 24 and governorswitch 2| remains effective. The gun will therefore continue firing until such time as the image Ia engages with the central brush l3 whereupon the circuit to the firing solenoid |9 is interrupted and firing ceases. This occurs at the instant at which the gun is immediately within the unsafe firing zone.

' If the turret continues to be traversed in the same direction the image I la will move across the central brush whereupon two circuits are simul taneously completed: the one circuit comprises central brush I3, image-cylinder I6, brush 24, and governor-switch 2| and the other circuit comprises central brush I3, lateral brush M and selector switch 7 l8. Each such circuit includes firing solenoid l9 so that upon brush I3 leaving image I la firing re-commences. Each image l, to: is so constructed and dimensioned that whilst the turret is being rotated at the slow-rate, it is impossible for the gun to fire so as to hit an object within the unsafe zone of fire although in certain circumstances they For instance, if at the instant the firing circuit is interrupted the striker pins of the guns are about to engage the primers of the bullets then these shots will be fired within the unsafe zone of fire. It is only necessary, however, to make the image of such a. size that under these or similar circumstances the bullets cannot hit an object within the unsafe zone of fire. Whether this will happen however, is dependent upon the rate of traverse. As this is increased it is necessary to make the image larger. Accordingly in gun turrets having a low and a high rate of traverse it is necessary to ensure, on the one hand, that the firing circuit is interrupted at all times as late as is pos-- sible so that the field of fire is as great as possible, and on the other hand, that such interruption takes place earlier with a high rate of traverse than with a low rate of traverse.

In the construction described with reference to Figure 1 the governor-switch 2| is set to open when the high-rate of traverse comes into being. Accordingly the firing circuit cannot be completed through the contact 24 but only through the central brush t3, the image-cylinder III, the leading brush of the two lateral brushes I2, M; the selector-switch [8, the firing solenoid l9, bat-- te'ry m and firing switch l5; This circuit is broken when a lateral brush is engaged by the image. The firing circuit is thus interrupted earlier point of time than when the low-rate of traverse is operative by an amount which is equivalent to the time taken by' the image-cylinder to move at the high-rate of traverse through the angular distance between the central and lateral brushes.

It will. be appreciated that. the particular circumstances described above of being able'tofire' within an unsafe zone although the. firing circuit is broken, does not occur when the gun is movedout of the unsafe zone into'a safe field of Accordingly it is desirable that the gun immediately commences to operate when the fringe of the field of fire is reached and that no lapse of-time in doing so occurs. This will occur provided that the firing circuit is completed im mediately the central brush leaves the image and engages the conducting image-cylinder 10. Since the lateral brush through which the firing circuit is completed at high-rates of traverse is in advance of the central brush, it both engages and leaves the image before the central brush and firing will take place as soon as the central brush i3 leaves the image.

It will be appreciated that when the turret is rotated in the opposite direction to that referred to above, the image-cylinder ii) will rotate in the opposite direction to the arrow A. At the same time the selector-switch l8 will engage the contact it so that the image Ii will be brought into engagement with the lateral brush l2 before engaging the central brush I3.

In Figure l the chain dotted image lib represents the enlarged field of unsafe fire due to increase in the speed at which the gun is trained upon a target. The enlargement to the right hand side of the image I la so as to produce image lib is effected when the image cylinder l0 rotates in the direction of arrow A and when the firing circuit is completed through brushes I3 and I 5. Similarly the enlargement on the left hand side of the image 1 la to produce the image his effected when the image cylinder II] is rotated in the opposite direction to arrow A and when the firing circuit is completed through brushes !2 and I3. Similar considerations apply to the lower image i i shown on the cylinder.

A practical embodiment of the mechanism of Figure l is shown in Figure 2. This construction is adapted for use in a gun turret part of which is generally indicated by the reference numeral as having a pair of spaced parallel guns one of which is indicated at 4!. With such a twin gun installation it is necessary to provide mechanism for individually controlling the firing of each gun so that it does not fire within the unsafe zone. In the construction shown the fixed gear ring of the turret referred to above is indicated at 25 whilst the turret support bearing is shown at 2. Engaging with said gear ring is a gear 25 so that upon rotation of the turret relative to the fixed gear ring 25 the gear 26 is rotated transmits to the image-cylinder as through gears 21, 28. The image-cylinder I0 is carried upon a central tube 29 which is supported at its lower end in a bearing 30 and at its upper end by hearing 3 i. The gun is pivotally mounted as at 32 and is connected with rod 35 by means of a link 33 and arm 34. The rod 35 is received bya socket 43 having a transverse pin 4'4 which passes through slots 45- in tube 29 and is attached to cap 56 carried by the cylinder l0 so that the gun and cylinder are raised and lowered' together. The image-cylinder ill is divided into an upper and lower portion, the upper portion of which carries the images H which are associated with one gunwhilst the lower portion carriesthe images associated with the other gun. B'o'th parts of the cylinder are provided with the brushes IE, IS, i l and 24- described with reference to Figure l. The brushes associated with the upper part of the cylinder are spaced apart from the brushes associated with the lower part of the cylinder by an amount slightly greater than half the depth of the image-cylinder l8. Both sets of brushes are secured tea carrier 36 which surrounds the image-cylinder Iii and is supported by the gun turret structure. The operation of the upperand lower part of the mechanism in stopping and starting the firing of its associated gun is as described with reference to Figure 1.

I claim:

1. A gun installation comprising a gun, driving means for training the gun on to a target at more than one speed, a control for regulating the driving means, a conducting plate representing the total field of fire of the gun, a central and a pair of lateral contacts disposed one on each side of the central contact said contacts being simultaneously, relatively movable over the conducting plate to reproduce the training movements of the gun, an insulated area on the plate representing the unsafe field of fire of the gun, a switch movable into series with either lateral brush and actuated by the control for the guntraining means, a switch in series with the central contact, a governor driven by the gun-training means and adjusting the central-contact switch, a firing circuit being completed through the central and a lateral brush, the centralcontact switch being opened by said governor when the gun-training means moves the gun at a predetermined speed.

2. A gun installation as claimed in claim 1 wherein the conducting plate is constituted by a cylinder which is rotated with traverse of the gun and raised and lowered with movements of elevation of the gun.

3. A gun installation comprising a gun, power means for training the gun on to a target at more than one speed, an electric circuit for controlling the firing of the gun, an interrupter mechanism forming part of said circuit to stop the gun firing when the latter is aimed to within a predetermined unsafe field of fire when being trained at a normal speed, means responsive to the speed at which the gun is trained on to the target and a switch mechanism forming part of the interrupter mechanism said switch mechanism being actuated by said speed-responsive means automatically to interrupt the firing of the gun before the latter is aimed to within the unsafe field of fire with increase in the speed at which the gun is trained beyond said normal speed.

4. A gun installation comprising a gun, power means for training the gun on to a target at more than one speed, an electric circuit for controlling the firing of the gun, an interrupter mechanism forming part of said circuit to stop the gun firing when the latter is aimed to within a predetermined unsafe field of fire, means responsive to the speed at which the gun is trained on to the target, a switch mechanism forming part of the interrupter mechanism said switch mechanism being actuated by said speed-responsive means, automatically to interrupt the firing of the gun before the latter is within the unsafe field of fire with increase in the speed at which the gun is trained beyond said normal speed and a selector switch in the circuit of said switch mechanism said selector switch being actuated by the gun-training means to arrange the switch mechanism so that the automatic earlier interruption of the firing circuit occurs only on the side of the unsafe field of fire which the gun first approaches.

5. A gun installation comprising a gun, power means for training the gun on to a target at more than one speed, an electric circuit for controlling the firing of the gun, a conducting plate forming a part of said circuit and representing the total field of fire of the gun, a contact relativel movable over the conducting plate to reproduce the training movement of the gun, an

insulated area on the plate representing the un- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Soenke Sept. 24, 1946 OTHER REFERENCES Flight magazine, February 4, 1943, pages 125- 126.

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